FC8T5/WW - 22 Watt - T5 Circline Fluorescent Tube - 2700K

Determine the wattage of the bulb you are trying to replace. This information should be marked on your existing bulb. If by chance it is rubbed off or not shown, always check your fixture for the maximum wattage it can handle. This information is usually located within the fixture, often near the socket.

Figure out the bulb size. In the case of circlines, you will need the diameter of the bulb. Diameter is a unit of measurement found by measuring from side to side through the center of the object. The most common sizes include T5, T9, and T6 – where the T stands for “tubular” and the number is a measurement in eighths of an inch. For example, a T5 is a tubular bulb that is 5/8” in diameter. Also, the number after "FC" usually determines the diameter so an FC12 is 12 inch in diameter.

It is especially important to take note of the pin configuration. The pins must be the same as the replacement bulb in order to fit back into the existing fixture. Not only will you need to know how many pins the bulb has, but where exactly on the lamp they are positioned.